Casting apparatus for connecting a battery plate to a metal strap

ABSTRACT

Casting apparatus 10 includes a lead pot 11, a pump unit 12 and a mould block 13, having feed duct 14. The feed duct 14 communicates with the pump unit 12 by means of a supply passage 17, which is also connected to an overflow outlet 18, which can be closed by a dump valve 19. In normal operation the level of the lead in the feed duct is kept to a datum level 23 defined by the overflow. During `pouring` however the dump valve 19 is closed.

BACKGROUND OF THE INVENTION

This invention relates to casting apparatus of the type for connecting abattery plate to a metal strap or post.

Such apparatus was described in British Patent No. 2,023,471B. In thisarrangement a pump 13 delivers a metered shot of lead through an inletvalve 203 into a feed duct 52 causing lead to overflow into mouldcavities 51. A dump valve 82 is then opened and the lead in the feedduct 52 falls back to a datum or constant head level defined by thelevel of the dump valve. Whilst this was a considerable improvement overexisting casting arrangements certain problems have been experienced.First the inlet valve has a tendency to become clogged so that it doesnot seat properly. This results in the feed duct draining down into thelead pot and as a result the next "shot" of lead delivered by the pumpresults in insufficient filling of the cavities. Further the shockwaveresulting from the delivery of the metered shot of lead causes ripplesin the feed duct and hence incomplete filling of the cavities.

SUMMARY OF THE INVENTION

The present invention consists in apparatus for connecting a batteryplate to a metal strap or post, including a mould having at least onestrap or post cavity and a molten-metal feed duct adjacent thereto, aweir between the feed duct and the cavity, means for deliveringmolten-metal to one end of the feed duct including a pump forsubstantially continuous operation and a dump valve for allowing metalto flow out of the duct to a predetermined datum level when open and forcausing metal to flow through -the weirs into the cavity, when closed.

By running the pump substantially continuously or completelycontinuously the shockwaves can be removed. In this constant runningarrangement the overflowing of the lead from the feed duct into thecavities can be achieved in a number of ways. First the pump can be runat a single speed and overflow is achieved simply by closing the dumpvalve. This leads to a rather high circulation of lead and hence oxideformation. Secondly the pump may be run at at least two speeds; a firstlow speed which is designed simply to prevent the feed duct leaking downinto the pot and a second high speed which will deliver an appropriateamount of lead into the feed duct for the cavities to be filled Bytiming the period of the second high speed and the operation of the dumpvalve the lead could be metered quite precisely. Thirdly the apparatusmay include an inlet valve between the pump and the feed duct. In thiscase if the inlet valve becomes clogged then the pump will prevent anyleakage from the feed duct into the pot, whilst the open dump valve willprevent the feed duct overflowing. Fourthly, and indeed preferably thepump may be switched off for a very short period of time after the leadhas flowed into the cavities, in order to increase the effective headacting on the lead in the duct and hence the rate at which thepredetermined datum level is achieved.

In a preferred embodiment the pump is an impeller pump and means areprovided for closing the dump valve only when the cavities are to befilled. The means for closing the dump valve may operate in response orin timed relationship with the opening and closing of the inlet valve.Alternatively in the situation where there is no inlet valve the meansfor closing the dump valve may operate in relation to the pump speed orsome other cyclic element in the casting apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be performed in various ways and specific embodimentswill now be described, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 is a diagrammatic side view of a casting apparatus;

FIG. 2 is a sectional view through the mould block of FIG. 1; and

FIG. 3 illustrates an alternative form of dump valve.

DETAILED DESCRIPTION OF THE INVENTION

The apparatus generally indicated at 10 comprises a lead pot 11, a pumpunit 12 and a mould block 13.

The mould block 13 is essentially identical to that described in theprevious Application but briefly it comprises a feed duct, 14 separatedfrom mould cavities 15 by weirs 16. The feed duct communicates with thepump unit 12 by means of a supply passage 17, which is also connected toan overflow outlet 18, which can be closed by a dump valve 19.

The pump unit includes an impeller pump 20 and an inlet valve 21. Theimpeller pump 20 draws lead in from the lead pot 11 through an inlet 22and, when the inlet valve 21 is open, feeds lead up into the supplypassage 17 and hence into the feed duct 14.

In normal operation the level of lead in the feed duct 14 is kept to adatum level 23 defined by the overflow outlet 18. When lead is to bepoured into the mould cavities 15, the dump valve 19 closes the overflowoutlet 18 and the inlet valve 21 is opened allowing a sustained flow oflead into the feed duct 14 so that the lead overflows the weirs 16. Thedump valve 19 is then opened and the inlet valve 21 closed (and the pumpmay be momentarily switched off) so that the lead in the feed duct fallsback below the height of the weir 16 once sufficient lead has beenpoured into the cavities 15.

If, however, the inlet valve 21 becomes clogged so that it no longerseats properly any downwardly leakage from the supply passage isprevented by the flow of lead through the resultant gap up into thepassage 17. If the rate of flow is such that excessive lead is receivedin the feed duct 14 then this will be regulated by the open overflowoutlet 18 which maintains the datum level. This method of operationsaves a considerable downtime in the apparatus, because currently pumpsare having to be stripped out once a week.

As has been mentioned above the alternative operations can be achievedin an arrangement omitting the inlet valve 21. Both valves are operatedby hydraulic rams 24, 25 against springs 26, 27. The dump valve ispreferably arranged to fail open.

In the drawings the dump valve is shown as a flap pivoted about an axisextending generally parallel to the direction of flow through the valve.Alternatively it may be pivoted about a transverse axis, so it closesagainst the flow rather than `slicing` across it. This means it is lesslikely to become jammed by any clog build up. A further possibility isshown in FIG. 3 in this case the dump valve 19 comprises a needle valveelement 30 which locates in an `open well` outlet 31 at the head ofsupply passage 17. The advantage of this arrangement is that it reducesthe surface area of the lead which is exposed to the air and henceoxidisation and clogging.

I claim:
 1. Apparatus for connecting a battery plate to a metal strap orpost, including a mould having at least one strap or post cavity and amolten-metal feed duct adjacent thereto, a weir between the feed ductand said at least one cavity, means for delivering molten-metal to oneend of the feed duct including a pump for substantially continuousoperation and a dump valve for allowing metal to flow out of the duct toa predetermined datum level when open and for causing metal to flow oversaid weir into said at least one cavity, when closed.
 2. Apparatus asclaimed in claim 1, wherein there is an inlet valve between the pump andthe feed duct.
 3. Apparatus as claimed in claim 1 wherein the pump is animpeller pump.
 4. Apparatus as claimed in claim 2 further includingmeans for closing the dump valve only when said at least one cavity isto be filled.
 5. Apparatus as claimed in claim 4, wherein the means forclosing the dump valve operates in response or in timed relationshipwith the opening of the inlet valve.
 6. Apparatus as claimed in claim 1,including means for driving the pump at more than one speed. 7.Apparatus as claimed in claim 6, further including means for closing thedump valve when the pump is accelerated.